异关节总目（学名：Xenarthra），又称贫齿总目。原始真兽类之一，是现存最古老的真兽类，保存真兽类原始特征和独特的特征如脊柱后部的胸椎和腰椎上有附加关节。由于从真兽诞生的初期就已经分化了出去，其成员之间差异较大，成员包括少数有鳞甲的犰狳，行动最慢的树懒及舌头最长的食蚁兽等。原本还包括土豚和穿山甲，但后来证实土豚和穿山甲与此目没有太大关系。本目和多数胎盘类哺乳动物相差都很远，近亲极少。已灭绝的成员包括雕齿兽和大懒兽等。较旧的书籍将本目列为「贫齿目」（Edentata），但目前已将其提升为总目，并将当中分别较大的分为2个目，分别是有甲目（包括犰狳科和已绝灭的雕齿兽科）及披毛目（包括树懒亚目和蠕舌亚目）。

The superorder Xenarthra is a group of placental mammals, extant today only in the Americas and represented by anteaters, tree sloths, and armadillos. The origins of the order can be traced as far back as the Paleocene, as early as 59 million years ago in South America. Xenarthrans developed and diversified extensively in South America during its long period of isolation in the early to mid Cenozoic Era. They invaded the Antilles by the early Miocene and, starting about 9 Mya, spread to Central and North America as part of the Great American Interchange. Nearly all of the formerly abundant megafaunal xenarthrans, such as ground sloths, glyptodonts, and pampatheres, became extinct at the end of the Pleistocene.